402 Philippine Journal of Science m» 



Many cells have been encountered in which the meganuclei 

 have undergone marked changes in shape and appearance. In 

 these cases the nuclei have become spherical or globular and the 

 chromatin is condensed into deeply staining bands or clumps, in 

 the meshes of which is seen clear, achromatinic material. The 

 micronucleus in these cases seems to be sunk deeply into the 

 substance of the meganucleus. 



^sms? a 



Fig. 4. a and b, Early stages in inclosure of micronucleus in meganucleus ; c, later stage. 



Other individuals have been seen lacking even a trace of either 

 nucleus, and there are those in which either one or the other 

 nucleus is absent. In such animals there can be seen in the 

 endopiasm fragments of stained substance, possibly of the nature 

 of chromatin, and in one case there was observed (see fig. 5, c) 

 a structure which, to all appearances, was the membrane of the 

 meganucleus lacking its chromatin contents. It is impossible 

 at present to arrive at any definite conclusion regarding the real 

 nature of these chromatinic bodies. Walker (12) has described 

 a process of sporulation in Balantidium falcifarum, and Stein (10) 

 hints at something of the same nature as occurring in B. ento- 

 zoon. The possibility of endomixis as described by Woodruff 

 and Erdmann must also be borne in mind, but the evidence here 

 is too slight to admit of a discussion of any of these points. The 

 possibility of these bodies being ingested organic matter must 

 likewise be considered. The disappearance of the micronucleus 

 may yet be explained by its incorporation into the meganucleus. 

 Apparent total absence of both nuclei in an uninjured individual 

 is mysterious unless explained on the basis of the fragmentation 

 of both nuclei, or as a result of abnormal division following 

 conjugation. 



The micronucleus is a small rounded or elongate body. It is 

 strikingly different in size and structure from that of either 

 Balantidium coli or B. falcifarum, but most closely resembles 

 Stein's figure of the nuclei of B. entozoon. When round it has 

 an average diameter of 3.3 fx, but when elongated it measures 

 6.88 ft by 4.22 /*. It seems likely that the normal shape is spher- 



